This invention is directed to pressure measurements, and more particularly to pressure transducers suitable for use in pressure measuring systems.
Systems for measuring pressure are used in a wide variety of fields. For example, civil engineers are often required to measure pore pressure, differential pressure, and total pressure in various pneumatic and hydraulic environments, often over extended periods of time. Because of the long time periods involved, the pressure measuring systems they use require the inclusion of a pressure sensing transducer that has long-term stability. More precisely, they require a small, accurate transducer that has low volumetric displacement, high linearity and zero-point stability.
In the past, a variety of small pressure transducers have been proposed for use in measuring systems of the type used by civil engineers and the like. For a variety of reasons, the prior art transducers have not been entirely satisfactory. One of the primary reasons prior art transducers have not been entirely satisfactory relates to their inclusion of rubber or metal diaphragms. The diaphragms are usually mounted in a chamber and sense differential pressure created by pressure applied to the opposing sides of the diaphragm. The diaphragm is, in turn, connected via a linkage to a mechanical indicating device. The result is a somewhat complex, relatively inaccurate, pressure sensing transducer and indicating device. These devices are relatively inaccurate for various reasons. First, their use of mechanical linkages creates the normal inaccuracies associated with such linkages, such inaccuracies increasing with wear and age. Second, diaphragms are relatively nonlinear, particularly as they approach the extremes of their path of travel. Moreover, diaphragms have a relatively short path of travel and, thus, a limited range of operation. These devices are not only inaccurate, they are also more complex than desirable. Further, such structures are often larger than desirable.
Therefore, it is an object of this invention to provide a new and improved pneumatic pressure sensing transducer.
It is a further object of this invention to provide a pneumatic pressure transducer suitable for use in systems designed to measure pneumatic or hydraulic pressure.
It is a still further object of this invention to provide a precision pneumatic null balance pressure transducer that is highly accurate, includes a minimal number of parts, is highly stable over a long period of time, has low volumetric displacement, has high linearity and has zero-point stability, yet is relatively small in size and inexpensive to manufacture.